Sony Mobile yesterday release new Android 4.3 Jelly Bean for XPERIA Z Ultra and here is workinf FTF with this firmware, Central Europe branding, so no bloatware, no customization.

Download -

Google Drive - https://drive.google.com/file/d/0B_d...it?usp=sharing

Mega - https://mega.co.nz/#!sVhB3SbA!a1pW-V...Ru-E9yo8Uaaefk

source - http://xperiafirmware.com/8-firmware...-z-ultra-c6833

Sony XPERIA Z Ultra with official Android 4.3 Jelly Bean firmware 14.2.A.0.290 - YouTube

It is following 5 guidelines showing HOW TO:

1. how to install the newest Android 4.2.2 for your phone (for Sony XPERIA Z Ultra C6833 it is currently the 14.2.A.0.290 firmware)
2. how to install the newest Android 4.2.2 for your phone (for Sony XPERIA Z Ultra C6833 it is currently the 14.1.B.2.257 firmware)
3. how to backup your original firmware customization (it is important in case you must send your phone to service)
4. how to unlock the bootloader (in case you want to install the custom kernels with recovery menu and much more)
5. how to relock bootloader on your phone

1. how to install the newest Android 4.3 for Sony XPERIA Z Ultra C6833

a) first of all, check your firmware version (if you already have the newest one, you do not need this tutorial)
b) download and install latest Flashtool from here (mirrors Google Drive or Mega)
c) download also latest Android 4.3 (mirrors Google Drive or Mega) for Sony XPERIA Z Ultra
d) paste the ftf file downloaded in step c) to folder „Firmware“ included in the XPERIA Flashtool
e) open the XPERIA Flashtool, click on flash and choose downloaded firmware, than click ok. Important - if you do not want to delete any data of your phone, just uncheck flashing userdata.sin file. All data will remain in your phone, but sometimes it can cause additional troubles. So it is better (and I recommend that) to do the backup of your personal data, than proceed with clean instalation and then restore your personal data.
f) turn off your phone and when Flashtool shows pop up window, connect phone to PC with holding volume down button
g) after few minutes all is done and your phone gets the new firmware

Sony XPERIA Z Ultra with official Android 4.3 Jelly Bean firmware 14.2.A.0.290 - YouTube

2. how to install the newest Android 4.2.2 for Sony XPERIA Z Ultra C6833

a) first of all, check your firmware version (if you already have the newest one, you do not need this tutorial)
b) download and install latest Flashtool from here (mirrors Google Drive or Mega)
c) download also latest Android 4.2.2 (mirrors Google Drive or Mega) for Sony XPERIA Z Ultra
d) paste the ftf file downloaded in step c) to folder „Firmware“ included in the XPERIA Flashtool
e) open the XPERIA Flashtool, click on flash and choose downloaded firmware, than click ok. Important - if you do not want to delete any data of your phone, just uncheck flashing userdata.sin file. All data will remain in your phone, but sometimes it can cause additional troubles. So it is better (and I recommend that) to do the backup of your personal data, than proceed with clean instalation and then restore your personal data.
f) turn off your phone and when Flashtool shows pop up window, connect phone to PC with holding volume down button
g) after few minutes all is done and your phone gets the new firmware

Sony XPERIA Z Ultra - první phablet se Sony Mobile moc povedl - YouTube

3. how to backup your original firmware customization

a) if you do not want to lose warranty of your phone, first thing you have to do is to backup your original customization
b) download Sony Update Service (SUS) and reinstall firmware of your phone (backup your data first)
c) after that, go to SUS folder in Program Files and search for folder db/some Number/blob_fs, there you find 3 files, which names start FILE
d) download and install latest Flashtool from here (mirrors Google Drive or Mega)
e) paste the three files, which names start FILE, from blob_fs folder to folder „Firmware“ included in the XPERIA Flashtool
f) open the Flashtool, click on Advanced, choose decrypt files and put all three files from blob_fs folder to the right columm
g) click ok and after approx. one minute a pop up Window will appear via Flashtool
h) mark all files and transfer them to the right column, than fill in a box in the right upper corner (fill in what you want, it is just for you)
i) now click ok and Flashtool will create backup of your original firmware customization, that you can anytime flash to your phone

you tube : U

5. how to re-lock your bootloader

a) download and install latest Flashtool from here (mirrors Google Drive or Mega)
b) start Flashtool and click on BLU button on the top
c) turn off your phone and when Flashtool shows pop up window, connect phone to PC with holding volume down button
d) just click on relock button and your bootloader is locked for now

Sony XPERIA Z Ultra versus Sony XPERIA Z - YouTube